"Z" 's & "V" 's do not have asofter compound. That is one of the myth's in the world of tires. There is a tremendous difference (night & day) in a race tire which could have a softer compound (completely dependant on application/surface racing on/weather conditions/etc.) and a street performace tire. There are to many reasons to list how & why a high performace tire provides better handling and usually shorter tread life, but softer compound is not one of them.